An unidentified male Muni ticket agent was arrested yesterday afternoon after allegedly punching a young woman.

"[T]he incident started as a verbal altercation but developed into a fight in which the ticket agent allegedly punched one of the two sisters, a juvenile," reports CBS 5/BCN. "It appears at least one of the sisters then threw a soda can at the ticket agent."

SFPD Sgt. Lyn Tomioka said that "[t]he preliminary investigation indicates the ticket agent was the aggressor." It all started, Tomioka explained, when the agent questioned the age of one of the sisters. "The ticket agent had concerns about the ages and the reduced rate ticket and did ask that question, 'How old are you?' The juvenile didn't have identification to verify her age," so the agent wouldn't let her through, which is when things started to heat up between the two.

ABC 7 reports that eyewitnesses say the two sisters enter the agent's booth and start striking him. Then, "according to a witness who didn't want to be identified, the Muni station agent just lost it and started fighting as if he were up against two grown men."

Both the juvenile and the Muni employee were taken to a local hospital to be treated for minor injuries.